Please add new recipe of clay that is using dross.
This will add a use for a dross, helping to sink some unused materials, as well as buff spiraling by making metal quality affect clay quality, which in it's turn affect mold for anvils.
Or, in case it's better to avoid affecting other clays quality by that, let it be molding material, or create craftable material from dross that allows mold crafting.
inb4 I know it's not viable irl.